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Step 6

Racking force provided by diagonal bracing for wind direction 1

Example one - Three bracing panels

Plan of a house with two bracing panels marked along one of the long external walls and one marked along the other long external wall.

Bracing of lengths 2.2 m, 2.1 m and 2.1 m (all walls <2.4 m)

Total length of bracing = 6.4 m

Racking force for bracing = 6.4 x 0.8 kN/m = 5.12 kN

So the racking force provided by the three bracing panels in this example is 5.12 kN.

Example two - Five bracing panels

Plan of a house with two bracing panels marked along one of the long external walls, one marked along the other long external wall, and two marked along internal walls.

For walls > 2.4 m, use 2.4 m long bracing panels

Additional bracing 2.4 + 2.4 = 4.8 m

4.8 m of bracing x 0.8 kN/m = 3.84 kN

Putting this all together for the five braces:

5.12 + 3.84 = 8.96 kN total racking force of five bracing panels

Additional racking force required = 12.9 - 8.96 (using the wind racking force of 12.9) = 3.94 kN

Racking force provided by diagonal bracing for wind direction 2

Example - All bracing panels are 2.4 m or greater.

Plan of a house with two bracing panels marked on each of the two shorter external walls, and seven on the internal walls.

11 braces x 2.4 = 26.4 m

26.4 m of bracing x 0.8 kN/m = 21.12 kN

Additional racking force required = 26.2 - 21.12 (using the wind racking force of 26.4) = 5.28 kN

If the total racking forces have not been achieved you need to assess the impact of nominal bracing.